Fans and fan frames

ABSTRACT

A fan with a fan frame and an impeller. The fan frame includes a housing and a motor base. The housing includes a passage. The passage forms an air outlet and an air inlet on both ends of the housing. The motor base is disposed in the housing. The impeller is disposed on the motor base. When the motor base is at the air outlet or the air inlet, the bottom of the motor base locates on a plane different from that of the air outlet or the air inlet. The motor base is raised into the housing, increasing the area of air flow intake or discharge. Additionally, during the operation of the fan, noise, caused by vibrations generated by rotation of the impeller and transferred to an exterior system via the motor base, can be reduced.

The present invention is a continuation-in-part application of theparent application bearing Ser. No. 10/799,420 and filed on Mar. 12,2004. Also, this Non-provisional application claims priority underU.S.C. § 119 (a) on Patent Application No(s). 093133821 filed in Taiwan,Republic of China on Nov. 5, 2004, the entire contents of which arehereby incorporated by reference.

BACKGROUND

The invention relates to fans and fan frames, and in particular to fansand fan frames capable of reducing noise.

AS performance of electronic devices is promoted, heat dissipationapparatus or systems are indispensable and are thus provided in theelectronic devices. If heat generated by an electronic device cannot beefficiently dissipated, performance of the electronic device maydeteriorate or the electronic device may be damaged. A heat dissipationapparatus thus plays an important role in removing heat generated byelectronic devices such as integrated circuits (ICs). With promotion ofpackage techniques, the area of integrated circuits decreases. Heataccumulated in the integrated circuit per unit area increasesaccordingly. Therefore, a heat dissipation apparatus with highheat-dissipating efficiency is required on the integrated circuit.

Fans are widely used in various heat-generating systems. FIG. 1A is aschematic cross section of a conventional fan, and FIG. 1B is aschematic view showing the fan of FIG. 1A applied to an exterior system1. A conventional fan 10 includes a frame 11, an impeller 14, and amotor (not shown). The impeller 14 further includes a hub 15 andmultiple blades 16 radially connected to the hub 15. The motor isdisposed inside of the hub 15.

The impeller 14 and motor are in the frame 11, and the impeller 14 isdriven by the motor to rotate. The motor base 12 is connected to theframe 11 by a plurality of ribs 13 and the ribs support the motor base12.

As shown in FIG. 1B, when the fan 10 is applied to a heat-generatingexterior system 1, the motor base 12 locates on the same plane as theframe 11 such that space required by outtake airflow is limited, theamount of airflow cannot be increased and noise generated by the fan 10cannot be reduced. Moreover, the fan 10 is fixed on and combined to aheat-generating device 2 in the exterior system 1 by screws penetratingthe frame 11. During the operation of the fan 10, vibrations generatedby the motor and rotation of the impeller 14 are transferred to theheat-generating device 2 and the exterior system 1 via the motor base 12and ribs 13, thereby generating noise. Also, vibrations generated by themotor may damage the heat-generating device-2 or other components in theexterior system 1.

SUMMARY

Accordingly, the invention provides an improved fan and fan frame toovercome the aforementioned problems. A motor base of the fan is raisedinto the housing of the fan, whereby increasing the area of air flowintake or discharge and providing a stable airflow. Additionally, noiseand vibrations, generated by rotation of an impeller and transferred toan exterior system via the motor base during the operation of the fan,can be reduced.

An exemplary embodiment of the invention provides a fan frame includinga housing and a motor base. The housing has a passage, and the passageforms an air outlet and an air inlet on both ends of the housing. Themotor base is disposed in the housing. When the motor base is at the airoutlet or the air inlet, the bottom of the motor base locates on a planedifferent from that of the air outlet or the air inlet. The fan framefurther includes a plurality of ribs connected between the housing andthe motor base to support the motor base. The cross section, width orthickness of each rib is varied along the direction from the motor baseto the housing. The housing further includes an outward expansionportion at the air outlet or the air inlet to increase the area of airflow intake or discharge. The motor base has a slope inclined radiallyto adjust the area of air flow intake or discharge, and the slope islinear or curved. Moreover, the motor base is a part of a system havinga fan assembly. The system is preferably a power supply, a server, or acomputer. The motor base forms a casing sidewall of a system, such as afan guard.

Another exemplary embodiment of the invention provides a fan, such as anaxial flow fan, including a fan frame and an impeller. The fan frame hasa housing and a motor base. The housing has a passage, and the passageforms an air outlet and an air inlet on both ends of the housing. Themotor base is disposed in the housing, and the impeller is disposed onthe motor base. When the motor base is at the air outlet or the airinlet, the bottom of the motor base locates on a plane different fromthat of the air outlet or the air inlet. The fan frame further includesa plurality of ribs disposed between the housing and the motor base tosupport the motor base. The cross section, width or thickness of eachrib is varied along the direction from the motor base to the housing.The housing further includes an outward expansion portion at the airoutlet or the air inlet to increase the area through which the air flowsinto and out of the housing. The outward expansion portion is formedwith a lead angle, a sloped angle, a lead and sloped angle, or a curvedangle. The motor base has a slope inclined radially to adjust the areaof air flow intake or discharge, and the slope is linear or curved.

Moreover, the fan frame is applied to a light source. The periphery ofthe passage is an inner surface, and the light is blocked frompenetrating the passage by the inner surface when light emitted by thelight source enters the passage. The outer edge of the impeller isparallel to the curved surface of the periphery of the passage. Theinner surface includes one or multiple gradually shrinking surfaces andgradually expanding surfaces so as to block the light emitted by thelight source. Alternatively, the inner surface includes a radially andgradually shrinking curved surface and a radially and graduallyexpanding curved surface, both of which have different curvatures. Inaddition, each blade of the impeller overlaps an adjacent blade in anaxial direction of the passage. The housing is substantiallyrectangular, circular, elliptical, or rhombic. The motor base may be apart of a system having a fan assembly. The system is preferably a powersupply, a server, or a computer. Additionally, the motor base forms acasing sidewall of a system, such as a fan guard.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1A is a schematic cross section of a conventional fan;

FIG. 1B is a schematic view showing the fan of FIG. 1A applied to anexterior system;

FIGS. 2A-2C are schematic views of fans of the first embodiment of theinvention;

FIG. 3A is a schematic view of a fan of the second embodiment of theinvention;

FIG. 3B is a schematic view showing the fan of FIG. 3A applied to anexterior system;

FIGS. 4A-4D are schematic views of fans of the third embodiment of theinvention;

FIGS. 5A-5D are schematic views of fans of the fourth embodiment of theinvention;

FIGS. 6A and 6B are schematic views of fans of the fifth embodiment ofthe invention; and

FIG. 6C is a schematic top view of an impeller of an embodiment of theinvention.

DETAILED DESCRIPTION

FIGS. 2A-2C are schematic views of fans 20 of the first embodiment ofthe invention. As shown in FIG. 2A, the fan 20, a preferred axial flowfan, includes a fan frame 21 and an impeller 24. The fan frame 21 is ahousing 21 having a passage 27, and the shape of the fan frame 21 issubstantially rectangular, circular, elliptical, or rhombic. The housing21 includes a motor base 22 and a plurality of ribs 23. The impeller 24includes a hub 25 and multiple blades 26 connected to the hub 25, andthere is a motor (not shown) disposed inside of the hub 25 for drivingthe impeller 24 to rotate. The impeller 24, motor base 22, and motor aredisposed in the housing 21. The impeller 24 is disposed on the motorbase 22 and is rotated by the motor. The ribs 23 are disposed betweenthe periphery 271 of the passage 27 and the motor base 22, forsupporting the motor base 22. The passage 27 forms an air outlet 211 andan air inlet 212 on both ends of the housing 21, and the air outlet 211and air inlet 212 are on a first hypothetical plane 221 and a secondhypothetical plane 222, respectively.

To overcome the drawbacks in which the bottom of the conventional motorbase 12 is coplanar with the fan frame, the motor base 22 is raised intothe housing 21 to form a displacement depth so as to provide a stableairflow. As shown in FIG. 2A, the motor base 22 is preferably disposedat the air outlet 211, and the bottom of the motor base 22 locates on aplane different from that of the air outlet 211 (first hypotheticalplane 221). Alternatively, the motor base 22 can be disposed at the airinlet 212, and the bottom of the motor base 22 locates on a planedifferent from that of the air inlet 212 (second hypothetical plane222).

When the motor base 22 is raised into the housing 21, the top of the hub25 disposed on the motor base 22 protrudes the second hypothetical plane222, as shown in FIG. 2B. However, operation and performance of the fan20 is not adversely affected. Further, considering of the situation thatthe fan 20 must be disposed coordinately with other components in anexterior system when the fan 20 is applied to the exterior system, thesize of the hub 25 is correspondingly adjusted. Thus, the top of the hub25 can just align the second hypothetical plane 222 (as shown in FIG.2A) or be slightly lower than the second hypothetical plane 222 (asshown in FIG. 2C) so that the hub 25 does not adversely affect operationof other components in the exterior system.

FIG. 3A is a schematic view of a fan 30 of the second embodiment of theinvention. Not only the motor base 32 is raised into the housing 31 toform a displacement depth, but also there is preferably an outwardexpansion portion 39 formed at the air outlet 311 or the air inlet 312to increase an area of air flow intake or discharge, thereby enhancingair pressure and airflow of the fan 30. Additionally, when the outwardexpansion portion 39 is disposed at the air outlet 311, deceleration andrectification of the airflow can be obtained. The outward expansionportion 39 can be formed with a lead angle, a sloped angle, a lead andsloped angle, or a curved angle. The ribs 33 can be directly connectedto the outward expansion portion 39 and motor base 32, for supportingthe motor base 32. Alternatively, the ribs 33 can be connected to otherportions, except the outward expansion portion 39, of the housing 31.

FIG. 3B is a schematic view showing the fan 30 of FIG. 3A applied to anexterior system 3. The fan 30 is applied to the exterior system 3 havinga heat-generating device 4 such as integrated circuits (ICs). Since adisplacement depth exists between the bottoms of the motor base 32 andthe outlet of the housing 31, a space for outtake airflow is enlarged,thereby enhancing the amount of airflow of the fan 30. Additionally, theoutward expansion portion 39 achieves deceleration and rectification ofthe airflow, thereby reducing the noise caused by turbulent flow field.Furthermore, since the bottom of the motor base 32 is higher than theoutlet of the housing 31, vibrations generated by the motor and rotationof the impeller 34 won't not be transferred to the heat-generatingdevice 4 or the exterior system 3 via the motor base 32 and ribs 33.Thus, the noise problem is solved and damage to components caused by theaforementioned vibrations can be prevented.

The motor base 32 can be considered as a part of a system having a fanassembly, or the motor base 32 forms a casing sidewall of a system, suchas a fan guard. The system 3 is a power supply, a server, or a computer.

The invention is not limited to the aforementioned structure. Forexample, in addition to the structural design of the motor base 32 andoutward expansion portion 39, the thickness, width, or cross section ofthe ribs can be designed to various requirements. Referring to FIGS.4A-4D, which are schematic views of fans 40 of the third embodiment ofthe invention. As shown in FIG. 4A, the housing 41 of fan 40 has anoutward expansion portion 49, and the multiple ribs 43, connected to theoutward expansion portion 49 and motor base 42, can be arranged inradial manner. The shape of ribs 43 can be, for example, columnar,curved, or streamlined.

Specifically, if the ribs 43 are connected to the motor base 42 and fanframe 41 in nonlinear manner, the cross section of the ribs 43 will notbe continuous. For ease of description, the cross sections of the ribsof all embodiments of the invention are completely shown and the bladesare shown in a clearer manner.

The thickness of each rib 43 is varied along the direction from themotor base 42 to the housing 41. As shown in FIG. 4A, the thickness ofeach rib 43 at the motor base 42 is smaller than that at the housing 41.Further, the thickness of each rib 43 gradually increases from the motorbase 42 to the housing 41. The change in the thickness of each rib 43can be linear slope gradual reduction or curve slope gradual reduction.

Alternatively, the thickness of each rib 43 at the motor base 42 isgreater than that at the housing 41. Further, the thickness of each rib43 gradually decreases from the motor base 42 to the housing 41, asshown in FIG. 4B. The change in the thickness of each rib 43 can belinear slope gradual reduction (as shown in FIG. 4B) or curve slopegradual reduction (as shown in FIG. 4C) Further, the thickness of eachrib 43 connecting to the motor base 42 and housing 41 is relativelygreater than that of a central part of the rib 43 and the thickness ofeach rib 43 is relatively less than that of the central part of the rib43, as shown in FIG. 4D. Furthermore, the thickness of each rib 43connecting to the motor base 42 and housing 41 is least.

When the impeller 44 rotates, airflow speed increases outwardly from theblades 46. Namely, the flow speed near the housing 41 is faster than thespeed near the motor base 42. Additionally, varied thickness design isapplied to each rib 43 so that the distances between each rib 43 and thelower edges of the blades 46 are different. In view of the direction ofthe airflow, the distances between the blades 46 and each rib 43 aredifferent. Accordingly, when the impeller 44 rotates, adverseinteraction between the blades 46 and the ribs 43 can be reduced. Theresistance of airflow and noise can thus be reduced.

The width of each rib 43 is designed according to the rotationaldirection of the blades 46. The width of each rib 43 is varied along thedirection from the motor base 42 to the housing 41. For example, eachrib 43 at the motor base 42 is thinner than at the housing 41. Further,the width of each rib 43 gradually increases from the motor base 42 tothe housing 41. The change in the width of each rib 43 can be linearslope gradual reduction or curve slope gradual reduction. In addition,the width of each rib 43 at the motor base 42 exceeds that at thehousing 41. Further, the width of each rib 43 gradually decreases fromthe motor base 42 to the housing 41. Similarly, the change in the widthof each rib 43 can be linear slope gradual reduction or curve slopegradual reduction. Alternatively, the width of each rib 43 connecting tothe motor base 42 and housing 41 is relatively greater than that of acentral part of the rib 43 while the central part of the rib 43 isthinnest through the rib 43. Furthermore, the width of each rib 43connecting to the motor base 42 and housing 41 is relatively less thanthat of the central part of the rib 43.

When the impeller 44 rotates, airflow speed increases outwardly from theblades 46. Namely, the flow speed near the housing 41 is faster than thespeed near the motor base 42. Additionally, the width of each rib 43 isvaried along the direction from the motor base 42 to the housing 41. Inview of the rotating direction of the blades 46, the width of each rib43 is varied. Accordingly, the influence caused by faster airflow at theribs 43 and housing 41 can be reduced by the aforementioned structuraldesign. The resistance of airflow and noise can thus be reduced.

The width and thickness of each rib 43 can be changed and betterdesigned. For example, In view of the rotating direction of the blades46 and for each rib 43, the portion with a smaller width can have alarger thickness. Thus, the strength of the housing 41 is not adverselyaffected due to thin ribs 43. For example, each rib 43 at the motor base42 is thinner than at the housing 41, and each rib 43 at the motor base42 is thicker than at the housing 41. Alternatively, the width of eachrib 43 at the motor base 42 exceeds that at the housing 41, and thethickness of each rib 43 at the motor base 42 is less than that at thehousing 41. The change in the width and thickness of each rib 43 cansimultaneously be linear or curved. Accordingly, the cross section ofeach rib 43 is varied along the direction from the motor base 42 to thehousing 41, whereby preventing noise caused by the resistance of airflowbetween the lower edges of the blades and the ribs.

FIGS. 5A-5D are schematic views of fans of the fourth embodiment of theinvention. The fan includes a raised motor base 52 and an outwardexpansion portion 59. Also, the motor base 52 includes a slope inclinedradially to adjust the area of air flow intake or discharge, wherebyoptimizing the flow field distributed in the fan. Therefore, the noiseof the fan can be further reduced and performance of the fan isenhanced. The motor base 52 expands outwardly from the bottom thereof,and the slope is linear (as shown in FIG. 5A) or curved (as shown inFIG. 5B). Alternatively, the motor base 52 inward shrinks from thebottom thereof, and the slope is linear (as shown in FIG. 5C) or curved(as shown in FIG. 5D).

Moreover, the fan can be applied to an external system with a lightsource L, such as a projector. Referring to FIGS. 6A and 6B, which areschematic views of fans of the fifth embodiment of the invention.Similarly, the fan includes a raised motor base 62 and an outwardexpansion portion 69. Additionally, in the housing 61, the periphery 671of the passage 67 includes an inner surface. When light emitted by thelight source L enters the passage 67, the light is blocked frompenetrating the passage 67 by the inner surface. The inner surface canbe a concave surface depressed toward a central axis of the passage 67so as to block the light emitted by the light source L. Or, the innersurface can be a convex surface protruded toward a central axis of thepassage 67, an outer edge of the impeller 64 is formed with a concavesurface opposing the curved surface so as to block the light emitted bythe light source L.

In addition, the inner surface may include one or multiple graduallyshrinking surfaces and gradually expanding surfaces, as shown in FIG.6A. Alternatively, the inner surface may include a radially andgradually shrinking curved surface and a radially and graduallyexpanding curved surface, both of which have different curvatures, asshown in FIG. 6B. As long as the inner periphery of the fan frame canmatch the curved blades, light emitted from the light source L can beblocked from penetrating the passage by the inner surface. Namely, theouter edge of the impeller 64 is parallel to the inner surface of theperiphery 671 of the passage 67. The gap between the blades 66 and thehousing 61 can be effectively sheltered. Thus, the fan can obstructlight from the light source L. Additionally, the curved outer edges ofthe blades 66 can increase the area of the blades 66, enhancing unity ofthe fan. Moreover, the displacement depth between the motor base 62 andthe bottom of the housing 61 can be adjusted by changing the innersurface of the periphery 671 of the passage 67. Thus, the flow field ofthe airflow between the impeller 64 and the housing 61 can be adjustedand the noise caused by a turbulent flow field effectively reduced.

FIG. 6C is a schematic top view of an impeller of an embodiment of theinvention. To effectively shelter the gap between the blades and thehousing, each blade 66 a of the impeller 64 overlaps an adjacent blade66 b in an axial direction of the passage. Also, each of the blades 66 aand 66 b has a flat, conical, curved or stepped edge.

In conclusion, the invention can overcome the drawbacks of theconventional fan in which the bottom of the motor base is coplanar withthat of the fan frame. In the present fan, the motor base is raised intothe housing of the fan frame to form a displacement depth, wherebyproviding a stable airflow. Additionally, the outward expansion portioncan increase the area of air flow intake or discharge. Thus,deceleration and rectification of the airflow can be obtained, and airpressure and air flow of the fan can be increased. Furthermore, ribswith a design of varied thickness, width or cross section not onlyenhance the strength of the fan. The distances between the lower edgesof the blades, but also reduce noise caused by adverse interactionbetween the ribs and the rotating blades. Moreover, the motor base caninclude a slope inclined radially, and the slope is linear or curved.Thus, the noise of the fan can be reduced and performance of the fanenhanced. Additionally, the housing with gradually shrinking surfacescan match the curved outer edges of the blades to shelter the gapbetween the housing and the blades. When the fan is applied to alight-emitting device to dissipate heat generated thereby, light leakageas in the conventional fan can be prevented.

While the invention has been described by way of example and in terms ofpreferred embodiment, it is to be understood that the invention is notlimited thereto. To the contrary, it is intended to cover variousmodifications and similar arrangements (as would be apparent to thoseskilled in the art). Therefore, the scope of the appended claims shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar arrangements.

1. A fan frame, comprising: a housing having a passage which forms anair outlet and an air inlet on both ends of the housing; and a motorbase disposed in the housing, wherein when the motor base is at the airoutlet or the air inlet, a bottom of the motor base locates on a planedifferent from that of the air outlet or the air inlet.
 2. The fan frameas claimed in claim 1, further comprising a plurality of ribs disposedbetween the housing and the motor base to support the motor base,wherein a cross section of each rib is varied along a direction from themotor base to the housing.
 3. The fan frame as claimed in claim 2,wherein a width of each rib is varied along the direction from the motorbase to the housing, or the width of each rib gradually increases ordecreases along the direction of from the motor base to the housing. 4.The fan frame as claimed in claim 3, wherein the width of each ribconnecting to the motor base and housing is relatively greater or lessthan that of a central part of the rib.
 5. The fan frame as claimed inclaim 2, wherein a thickness of each rib is varied from along thedirection of the motor base to the housing, or the thickness of each ribgradually increases or decreases along the direction of from the motorbase to the housing.
 6. The fan frame as claimed in claim 5, wherein thethickness of each rib connecting to the motor base and housing isrelatively greater or less than that of a central part of the rib. 7.The fan frame as claimed in claim 2, wherein the housing furthercomprises an outward expansion portion at the air outlet or the airinlet to increase an area of air flow intake or discharge.
 8. The fanframe as claimed in claim 7, wherein the ribs are connected to theoutward expansion portion, and the outward expansion portion is formedwith a lead angle, a sloped angle, a lead and sloped angle, or a curvedangle.
 9. The fan frame as claimed in claim 2, wherein the motor basecomprises a slope inclined radially to adjust an area of air flow intakeor discharge, and the slope is linear or curved.
 10. A fan, comprising:a fan frame comprising: a housing having a passage which forms an airoutlet and an air inlet on both ends of the housing; and a motor basedisposed in the housing; and an impeller disposed on the motor base,wherein when the motor base is at the air outlet or the air inlet, abottom of the motor base locates on a plane different from that of theair outlet or the air inlet.
 11. The fan as claimed in claim 10, whereinthe fan is applied to a light source, a periphery of the passagecomprises an inner surface, and when light emitted by the light sourceenters the passage, the light is blocked from penetrating the passage bythe inner surface.
 12. The fan as claimed in claim 11, wherein the innersurface is a concave surface depressed toward a central axis of thepassage so as to block the light emitted by the light source.
 13. Thefan as claimed in claim 11, wherein the inner surface is a convexsurface protruded toward a central axis of the passage, an outer edge ofthe impeller is formed with a concave surface opposing the curvedsurface so as to block the light emitted by the light source.
 14. Thefan as claimed in claim 11, wherein the outer edge of the impeller isparallel to the curved surface of the periphery of the passage.
 15. Thefan as claimed in claim 11, wherein the inner surface comprises agradually shrinking surface and a gradually expanding surface.
 16. Thefan as claimed in claim 11, wherein the inner surface comprises aradially- and gradually shrinking curved surface and a radially andgradually expanding curved surface, both of which have differentcurvatures.
 17. The fan as claimed in claim 11, wherein a maximum outerdiameter of the outer edge of the impeller exceeds a minimum innerdiameter of the periphery of the passage.
 18. The fan as claimed inclaim 11, wherein the impeller comprises blades with flat, conical,curved or stepped edges.
 19. The fan as claimed in claim 10, whereineach blade of the impeller overlaps an adjacent blade in an axialdirection of the passage.
 20. The fan as claimed in claim 10, whereinthe motor base is a part of a system having a fan assembly or the motorbase forms a casing sidewall of a system.